Abstract:

Mainly composed by amorphous silica and having higher activity,the residue from circulating fluidized bed ash detached Al₂O₃ with one-step acid dissolution method is ideal raw materials for preparation of silica,molecular sieve and Na₂SiO₃.The dissolving process of residue of fly ash in sodium hydroxide solution was studied.The influence of liquid-solid ratio,alkali concentrations,dissolving time and dissolving temperature on dissolution rate of SiO₂ and Al₂O₃ was also discussed.The results showed that the dissolving ratio of silica in residue of fly ash could be more than 93%,when the concentration of sodium hydroxide was 4 mol/L,the reactive temperature was 70 ℃,the liquid-solid ratio was 6,and the reactive time was 4 h.The solid residue from alkali leaching process of aluminum extraction residue was analysized by XRD.Results showed that almost all of amorphous silica in the residue dissolved into the lye,and the alkali residue was comprised of anatase,mullite and so on.

Key words: aluminum extraction residue from fly ash, alkali dissolution, silicon dioxide, aluminum oxide, dissolving rate